1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to encoding and decoding of an audio signal, and more particularly, to encoding an audio signal, in which continuation sinusoid signal information indicating the number of sub frames where continuation sinusoid signals exist is encoded in different ways according to index information of a frame, and decoding an audio signal.
2. Description of the Related Art
An audio encoding method is applied to parametric coding. Parametric coding expresses an audio signal by using a particular parameter. Parametric coding is used in the Moving Picture Experts Group (MPEG)-4 standard.
FIG. 1 is a diagram for explaining parametric coding. In parametric coding, an input signal is analyzed and parameterized. Referring to FIG. 1, an input audio signal is appropriately filtered by audio reading and filtering 110. Parameters for audio components in each domain are extracted by performing three types of analysis, i.e., transient analysis 120, sinusoidal analysis 130, and noise analysis 140.
The transient analysis deals with a dynamic audio change. The sinusoidal analysis deals with a deterministic audio change. The noise analysis deals with a stochastic or non-deterministic audio change.
The extracted parameters are formatted into a bitstream by performing bitstream formatting 150.